There has since ancient days been small boating, fishing and shipping businesses in Louth, including at Annagassan, which during the Potato Famine years, ferried many starving Irish who were destined for the ports of New York, Philadelphia, Havre de Grace and Baltimore. I do not know if boats sailed transatlantically from Annagassan, or merely connected to the presumably larger nearby deportation docks of Dundalk.
Now, for much of the year, Annagassan is mostly a couple of pubs, some village houses, fishing works and sheep farms, but it holds an occasional Viking Festival (recently interrupted by the plandemic) and a Viking 10K Coastal Run.
If you are in that area of Ireland, it's not a far drive either from Louth or from Dublin over to County Meath and Sláine (Saint Patrick's Hill), and nearby, the ancient pagan Hill of Tara.
When you say "small boating," is this what you mean (perfect size for a leprechaun)?
So a bunch of leprechauns may have come to the states?